Process of electrochemical precipitation op metals



14,849. 2 SHEETS-SHEET l.

mw//AI EIIIIIIIIlII"r E. R. HOLDEN.

K PROCESS 0F ELECTROCHEMICAL PRECIPITATION OF METALS.

APPLICATION FILED OCT. 30| 19I9.

A fm f@ leissued' Apr. 27, 1920.

n' WITNESS.'

E. TI. HOLDEN. y Pnocess or ELEcTrIocIIEIIIIIc/II PRECIPITATION of METALS.

APPL`ICAT|ON F|LED DCT- 30| |99.

Reissued Apr. 27,1920. 14,849.

2 SHEETS-SHEET 2.

6, |IIIIIIII /N VEN TOI? A TTU/MIE Y UNITED sTATEs PATENT oFFIoE.-

EDWARD ROYAL-HOLDEN, F LOS ANGELES, CALIFORNIA.

PROCESS 0F ELECTROCHEMICAL PECIPITATIQN QF METALS-.-

Specification of Reissued Letters Patent. Rei'ssued Apr. 27, 1920.

original application med oeteber 1o, 191s, serial ne. 124,902. Renewed November 5, 1917,- serial No.

200,456. Serial No. 334,552.

process for electrolytically treating solutions containing metallic substances and the attainment of a rapid, economical and eiiicient method of precipitating and' recovermgA v1 5 metals from solutions.

This process is more particularly adaptedto the'- precipitation of metals from chlorid, cyanid, sulfate or other dissolving solutions containingv gold, silver, copper -o'r other metals, either single or together. The essence of this invention resides lin the process of distributing and disseminating an electric current, hereinafter fully setv forth, and illustrated in the accompanying drawings, in which:

Figure 1 is a view in vertical section, partly in elevation, tof an' apparatus employed in carryingout my process, show-` ing a part .of the electrical device in diagram.

Fig. 2 is adiagrammatic view illustrating the electric lcircuits and the manner of distributing the electric current throughout an electrolyte. .i Fig. 3 is a view in horizontal section on a reduced scale, as seen on the line 3 3, of

ig. 4 is a detail in plan-of the revolvingl 'resistance coil carriage and the wiper con- Original No'. 1,269,565, dated June 11,

17.918.' Application for reissue iled October 30, 1919.-

drawing, I' have illustrated by a vertical sectional view, and in diagram, one embodiment `of a tank showing fully the manner of wiring; the resistance .Coils necessary'for the regulation of the current the various anodes and their respective distances from the cathode; a non-condhctingshaft, said shaft being constructed of any suitable material, such as hard wood, hard .,rulber or other material, not affected by acid or alkaline solutions, nor electrolysis, together with a copper, mercury or other negative cathode on the bottom of the tank.

More specifically in the drawing, A indi Cates a tank of any suitable material, pref-.

erably wood, about si'X feet in diameter, and e jv' twelve feet in depth, although other sizes l may be found advantageous. In this tank -a vertical shaft B of non-conducting material is mounted, and throughout its entire height at` equal distance apart, carries a number of metallicl paddles as anodes numbered from ltoy 9; anode 1 being placed just above a cathodeC,comprising a copper or other metallicfplate or mercury arranged to cover the` bottom of the tank. The paddles are here shown as comprising four bladesA to a set constituting a separate anode. By Arepeated .experiments I have found that in a tank twelve feet deep lled with. a solutioncontaining metals in solution, the bestelectrolytic precipitation is obtained when the metallic anodes are set about twelve to fifteen inches apart; the lowest anode l being siX to twelve inches, more or less, above the cathode'C'. The shaft isl rotated by gearing D or other suitable means. e.

On the upper part'of the non-conducting shaft is a circular metallic contact ring E f connected with a positive current of electricity, througha wiper vContact F connected with a conductor G leading frm one terminal of a source of `electrical supply or generator H; a conductor, I leading from the other terminal of the'generator tothe cathode C.- vOn the lower, end of the metallic contact ring E and attached thereto is a circular disk J 'of hard rubber or other nonconducting substance, Resting upon and attached to the disk J are separately wound individual resistance coils 1a to 9a, as shown in Fig. 2, there being oneresistance coil for each of the anodes attached to the shaft. The top of each resistance coil is Connected with the-contact ring E and the p ositive current of electricity passes from the contact ring into each resistance coil, the lower ends of which are resting on the disk J and each coil is connected with its own separate insulated Wire or conductor 1b to 9b, lead ing down through vthe electrolyte .to anv anode. Each one ofthes'e separate resistance coils is so Vwired as to convey a regulated and controlled volume ofV electricity to the anode to which it is attached; the separate coils being graded inv decreasing degreesnf resistance according toA the distance of the anodes from the cathode, for example, coilI .1a connecting with the lowermost anode l is of greatest resistance and coil 9a connecting with the uppermost anode of the least resistance,V with thev intermediate l coils stepped down in uniform degrees of resist? ance as the distance of the anodes from the cathode is increased, thus introducing an independent electric currentthrough eachv anode of such ampera'ge as will overcome the added resistance caused by the distance of each" anode from the cathode. Each anode thus becomes an independent one, capable of disseminating the necessary amount of current density through the solution to over- ,come the resistance caused by the distance of each anode from the cathodev whereby the electric current passing into the electro- -lyte is distributed throughout the whole solution in such 'a Ymanner that the metals in solution areimmediately andV uniformly liberated into metallic ions from their compound condition and are precipitated on the cathode; the detailed operation of which is hereafter more fully explained.

At the bottom .of the tank A is a draw off pipe K, for the `purpose of drawing off the mercury cathode or removing precipitates 'from the surface of any cathode used.' A

The shaft B extends through the bottom of the tank A and is supported by an prdinarystulingbox and the end of the shaft operates in an ordinary ball bearing box.

The anodes described and attached to the non-conducting shaft are made of any material best suited to the precipitation of the metals in rsolution and are positive to the;

metallic1 substances used as a cathode and p while revolving' inthe tank, also serve as agitato'rs for the solution, and lthrough th'e separate resistance coils which are 1n 'contact'with the Wires leading to-each anode,

disseminate throughout the electrolyte,fbe tween each anode and the cathode, the difsolution and for their precipitation and re covery and to increase the efficiency and potential conditions necessary in lconducting electricity Yinto a liquid, and for clearly eX- emplifying the improvement in the method of disseminating varying quantities of E. M.

F. to separate a'nodes throughout the elec-v trolyte, I herewith append the results of the following tests conducted for the purpose of advancing the art and to illustrate the improvements over those indicated in my previous Letters Patent granted'April 25th 1916, numbered 1,181,077, and entitled Process -of treating ores bearing precious metals. "s

I found by experiment in a tank three feet in Adiameter and nine feet in depth,

containing a solution carrying gold :and silverin solution, with suicient y'sodium chlorid present to establish the necessary conductivity and a current of positive electricity 'passing down through the electrolyte, by means of separate Wires attached to a'contact ring above, and connected with a number of anodes attachedto a non-couducting shaft, but Without using the resista-nce coilsA hereinbefore described, that the density of the current between the lowest anode 1 and the cathode was 69() times greater than ,the density of the current surroundingthe highest anode 9 at the top of the solution and that the several anodes from 2 to 9 inclusive indicated a constantly decreasing amount of vamperes vin propor-v tion to their increased distance from the cathode and had therefore only a trace or at best but a feeble precipitating action on the metallic compounds in 'solution above the lowest anode. f

In the above experiment the shaft wasre- Y volved with the anodes set about onefoot apart; the bottom anode 1 being siX inches above the cathode. y

The same unequal, densities prevailed throughout the solution when a direct, undivided and unaltered `current of 'electricity wfas conducted into the electrolyte through a conducting shaft on which a number of anodes set in the same manner as above described were attached.

Each of the anodes, above the lowest one, which was in vclosest contact 'with the cathode, showed a uniform proportional decrease in amperes, the density of the .current between the lowest anode l and the cathode was 4.14famperes per square foot ,of cathode surface, while the density of the current just 'below' the top anode 9 was process.

onl .006 amperes per square foot of cathode sur ace. y

The following table gives the vregistered ampere readings, indicated on a testing-ammeter, per square 'foot of. cathode surface, y

as registered by each anode separately, beginning `with the lowest anode 1 and shoW-' ing a decreased potential'at each anode in proportion tothe 4distance between each anode andthe cathode:

- Individual Distance Volts. anode readfrom ings. cathode.

v Amperes. 12 .00s 8'6" 12 '.009 7'6" 12 .014 6'6" 12 .D26 5'6" v12l f .041 4:6" 12 .060 3'6" The following experiments are herewith set forthV for the purpose of comparison` and toshow the detailed operation of and advantages derived by the present process.

experiment was conducted in the above tank which contained 4,500 lbs. of .20% potassium cyanid solution, carrying gold and silver in solution. The solution alsol contained: the necessary amount of sodium chlorid to establish the conductivity re uired. I he current' was then led through the Contact ring directly to each anode, passing thence through the electrolyte to the cathode for the purpose of precipitating the gold andsilver out ofthe solution and this operation continued for siX hours. After each hour a sanple of the solution was drawn through a pet cock in thefside of the tank just below anodes 1, '5 and 9.

`The solution obtained below anode 1 4at the end of `the first hour, showed that the gold and silver value of the solution had Idecreased 46% per ton of solution. The sample taken simultaneouslyv below anode1 5- showed that the gold and silver value had decreased 36% per ton of solution, while the sample taken simultaneously below anode 9 had decreased only 6% `per ton of l solution.' Samples taken at the end of the The sample taken below anode 1 at \th end ofthe sixth or; iinal hour showedthat the gold and vsilverL 'value of the solution had decreased 98.2% per ton of solution, While the sample taken simultaneously below anode 5 showed the gold and silver value had decreased per ton of solution,fwhile the sample taken simultaneously below anode 9 had decreased only 50% per ton of was then withdrawn and the solution thor oughly mixed and showed a total precipitation of only 74.4% of the gold and silver `from the original solution. K y

Another experiment was then made with a similar solution carrying the identical values in gold and silver per ton. The resistan'ce coils heretofore described were then put in contact on disk J and connected with the Contact ring E and the lead paddles as anodes. The resistance coils were wound with climax wire in such a manner as to deliver to each anode the necessary E. M. F..

so that the potential' at each anode ,was altered and maintained in the electrolyte in'proportion to its distance from the cathode, thereby regulating the potential ybetween each anode and the cathode, and producing throughout the solution, from the top to the bottom, the required amperage to establish the necessary potential simul' taneously in all parts offthe solution to d ecompose and i precipitate the metals from their compounds, with the following result:

` Individual Distance Volts. anode readfrom ings. cathode.

i Amperes. v Anode No. 9 12 2.50 8'6" 8... 12 2.36 7 6" .12 F2.22 66 12 2.08 '5'6" 12 1.94 4'6. fl Il 1 83 376i/ 12 l`.70 2'6" 12 1.62 1'6" Il 1.50 6H After the above regulated current had been disseminated ,throughout the electrolyte for one hour, samples of the solution rcorresponding" to those takenv Iin test one, were drawn just below anodes 1, 5 and 9. The solution taken vbelow-anode 1 .had decreased in value in gold and silver 48% per `ton of solution. The sample taken simultaneously justmbelow anode 5 showed the gold and silver value of the solution had decreased 44% per ton of solution, while the sample taken at the same time, just besolution. AThe ventire contents of the tank i low anode '9 had decreased 35%yper ton of desire, however, to limit himself to the ing and disseminating an electric current solution. Samples taken at theen-d of the secondf-third-fourth-ifth and sixth hours showed that the precipitation wasl proportionately uniform at all the respective anodes. The' samples taken at the end of the sixth or final hour showed that the -gold and vsilver value of the solution hadV decreased below anode 1, 99.9% per ton of solution, while the sample taken simultaneously just below anode 5 showed the gold.

and silver value had decreased 99.7% per ton o f solution, while the sample taken simultaneouslyvjust below anode 9Jshowed the gold and silver value had decreased 99.5% per ton of solution. p

A continuation ofthe operation of 'the current through the electrolyte for a longer period would have precipitated the trace of gold and silver remaining in the solution,

but the time required and the current costs yin recovering same commercially, precluded -carrying the operation further.

The second table above referred to shows a regulated increase of amperage from the bottom to thetop. The applicant does'not method of regulating the amperage so that the lowest amperage is at the bottom and the highest at the top, as indicated by this table, but may,regulate the amperage that the values of the table may be reversed, and

f the lowest amperage will be at the 'top and vthe highest at the bottom, or the amperage may be 'substantially vequal at each anode. The preferred method is to have thehighest amperage at the top, decreasing toward the" bottom, but my method broadly contemplates regulation of the amperage at different anodese in the solution. y

The use of ai non-conducting shaft, or one entirely constructed of non-conducting material and carrying no lcurrent into the electrolyte, makes possible the` dissemination of different E. M. F. through Various anodes at different points in the solution, with the result above described. p

The above described method of distribut is also adaptable to and greatly accelerates the dissolution of .metals and their compounds from ores in (for example) a cyanid electrolyte by the liberation of cyanogen,` at the cathode, according to the following well known equations thereby regenerating the solvent solution and maintaining maxim-um possible solvent efficency therein, throughout the operation,

which results in bringing about a very much more rapid and efficient dissolution of the metals and their compounds thancanbe ob? tained if the electric current is not distribf uted and disseminated by means of a plurality of anodes throughout the electrolyte. VSimilar regeneration of solvent is brought about when bromid, chlorin, sulfate or'other solvent is used.

I am aware ofthe fact that patents have thereto, producing and maintaining any desired density of current throughout the electrolyte, substantially as set forth.

2. The process of treating a solution containing metals, consisting in agitating the solution, in introducing an electric current into the solution at points at different distances from the cathode, and regulating the voltages to maintain any desired density of current throughout the solution.

B. A process of treating a solution containing metals, introducing electric currents into the solution at points at different distances from the'cathode, and regulating the voltage at each point in accordance with l its distance from the cathode. e

In testimony whereof .I have signed 'name to this specification.

EDWARD" RoifAL HoLDENL' 

